Conventionally, wellhead connections to pressure control equipment are typically made by either a hand union or hammer union. Wellhead operators engaging or disengaging these conventional types of wellhead connections place themselves in danger of injury. The pressure control equipment to be connected to the wellhead is typically heavy, and remains suspended above the wellhead operator via use of a crane. Interacting with the crane operator, a technician at the wellhead below must struggle with the suspended load as it is lowered in order to achieve the proper entry angle into the wellhead to make a secure connection. The wellhead operator must then connect the wellhead to the pressure control equipment, typically via a bolted flanged connection. The bolts must be tightened manually by a person at the wellhead, typically via a “knock wrench” struck with a sledgehammer in order to get the bolts sufficiently tight to withstand the internal operating pressure. During this whole process, as noted, the operator is in physical danger of injuries, such as collision with the suspended pressure control equipment load, or pinched or crushed fingers and hands when securing the connection.
Wellhead operators are exposed to similar risks of injury during conventional removal of the pressure control equipment from the wellhead. The removal process is substantially the reverse of the engagement process described in the previous paragraph.
Existing fluid connections have addressed the foregoing need in the well services industry to connect and disconnect pressure control equipment from the wellhead in a safe environment while minimizing the physical danger to human resources in the vicinity. Applicant's devices such as disclosed in U.S. Pat. Nos. 9,644,443 and 9,670,745 are examples of such existing fluid connections. FIGS. 1A and 1B in this disclosure illustrate examples of such existing fluid connections, and are based upon FIG. 2 in U.S. Pat. Nos. 9,644,443 and 9,670,745.
Embodiments of the fluid connections described in U.S. Pat. Nos. 9,644,443 and 9,670,745 may be rated up to 15,000 psi MAWP (maximum allowable working pressure), with diameters ranging from about 2″ to about 7″ ID. In practice, however, even though serviceable, embodiments rated over about 10,000 psi MAWP in over about 5″ ID have proven difficult to manufacture with consistent performance. Additionally, 10,000 psi MAWP in 5″ ID is generally recognized as a satisfactory service rating in wellhead pressure control applications.
Hydraulic fracturing has become an increasingly important technique used in the extraction of hydrocarbons from subterranean formations. Fluid connections are needed in hydraulic fracturing in order, for example, to facilitate flow of fracturing fluid into and out of wells via a wellhead. However, the fracturing process often calls for hydraulic fluid pressures and flow rates exceeding those typically seen in conventional wellhead pressure control applications. In some applications, hydraulic fracturing may call for 15,000 psi MAWP pressures in wellheads up to 8″ ID. This in turn translates into a requirement for fluid connections that are rated for such correspondingly higher hydraulic pressures and wellhead diameters. A need exists for a fluid connection design that is capable of consistently retaining higher pressures in larger diameter wellheads, in order to accommodate higher fluid flows at such fluid pressures. At the same time, such a fluid connection design should also be remotely operable in order to address personnel safety considerations near wellheads as described above.